A telephone ordinarily communicates with other telephones in a telephone network through a central switch, such as the switching system of a telephone company central office. Communication with the central switch ordinarily is accomplished using a conventional protocol, such as an industry standard ISDN protocol.
In most common telephone networks, a variety of special features are available to users in addition to the basic communication of voice and/or other data signals. For example, many public telephone companies offer their users features such as conference, hold, transfer, voice messaging, centrex, call forwarding on busy, call forwarding on idle, selective call forwarding and discounted calling plans for specific geographical regions. Telephone users commonly activate selected features by pressing predetermined keys or sequences of keys on their telephones.
Each telephone in a telephone network commonly has a set of special features assigned to it. Ordinarily, the set of special features assigned to a telephone corresponds to a "class of service" for that telephone. Some common protocols used in telephone networks provide for class of service information to be automatically downloaded to each telephone in the network upon installation of the telephone. Other standard protocols, however, do not provide for downloading class of service (COS) information to telephones. Examples of protocols that do not provide such downloading are the National ISDN 1 Protocol (NI1) and the European Telecommunications Standards Institute ISDN Protocol (ETSI; EURO-ISDN),
Where the protocol does not provide for downloading class of service information to each telephone, telephone users generally must determine which telephony features are assigned to their telephone in some inefficient manner. For example, a user may call the telephone company and request a list of features assigned to his telephone. A company service representative then generally looks up a "terminal service profile" for that telephone that specifies the features assigned to the telephone, and mails the information to the user. This technique is undesirable in that it requires the assistance of telephone company personnel and there can be a substantial delay between the request for a list of features and delivery of the list by the telephone company.
Alternatively, a user who has a general list of telephony features offered through his public switch may determine which features are specifically available to his telephone by trying each possible feature. The user can then keep a list of the features that were found to be operative. This technique is undesirable in that it requires the user to test each possible feature and document the results.
In addition to the above-mentioned disadvantages, each of these prior art techniques is inherently inefficient, time consuming, and likely to result in errors of transcription. A further disadvantage is that the telephone user is required to maintain a list of the features available to the telephone. Occasional users of the telephone may not have access to the list of features and will be left without a convenient means of determining which features are available to the telephone. In order to determine whether any change has been made in the features available to a telephone, the user must update the list, either by obtaining new information from the telephone company or by trial and error. Finally, after determining that a feature is available by examining the list of features, a user seeking to activate the feature must determine which keys or sequences of keys must be pressed to activate the feature, which may result in further delay if such information is not readily available to the user or if the user is unfamiliar with the keys on the particular telephone being used.
As a result of the above, there is a need for method and apparatus for enabling users of a telephone to efficiently determine which telephony features are assigned to the telephone, and a further need for efficient means for activating selected features assigned to the telephone.